The present invention is directed to circuit breakers, and more particularly to draw out interlock mechanisms therefor.
Industrial-rated draw-out circuit breakers include a pair of connectors (usually male) for each pole on one side of the breaker housing for electrically connecting the draw-out circuit breaker to a compartment, which in turn includes load and line straps for each pole, allowing the draw out circuit breaker to be connected in a power distribution circuit. This configuration allows the circuit breaker to be quickly and easily removed or replaced. The circuit breaker includes movable and fixed contacts for opening and closing the distribution circuit. For safety reasons, the contacts should be open when the draw out circuit breaker is inserted or removed.
Prior art interlock mechanisms have been proposed to prevent insertion or removal of a draw out circuit breaker while the contacts are closed. Such designs include circuit breaker operating mechanisms that are specially designed to cause the circuit breaker to xe2x80x9ctripxe2x80x9d when the draw out circuit breaker is inserted or removed from the compartment. However it is desirable to provide an interlock mechanism that can be easily added to a standard operating mechanism that is completely assembled to allow for more manufacturing flexibility and to reduce the risk of damaging the interlock mechanism due to handling damage. Furthermore, the design must easily interact with a draw out compartment with the ability to compensate for manufacturing variations.
The above discussed improved design is achieved by a draw out interlock mechanism comprising a draw out trip arm pivotally attached in a draw out circuit breaker and an interlock activating assembly attached to a draw out circuit breaker. The draw out trip arm comprises a first extension on a first end and a second extension on a second end. The extension is positioned to interact with a trip latch of the operating mechanism. The interlock activating assembly comprises an extended arm and a camming arm, which are pivotally attached to a pin supported by a mounting bracket attached to the draw out circuit breaker. The extended arm extends through an aperture in the draw out circuit breaker with an end thereof proximate to the second extension of the draw out trip arm. The camming arm is adapted to interact with a camming surface attached to the draw out circuit breaker compartment such that when the draw out circuit breaker is inserted into the compartment, the carnming arm and the extended arm rotate clockwise, the extended arm interacting with the tab formed on the draw out trip arm causing the draw out trip arm to rotate in counterclockwise, which in turn causes the extension of the draw out trip arm to interact with the trip latch causing the draw out circuit breaker to trip, opening the contacts in the circuit breaker.